Coating compositions containing tetramethyl cyclobutanediol

Abstract

Disclosed are solvent borne thermosetting coating compositions that contain a curable polyester resin blended with an acrylic copolymer, a crosslinker, and a solvent. The polyester resin contains 2,2,4,4-tetramethyl-1,3-cyclobutanediol and exhibits good dry time, compatibility with acrylic resins, sag resistance and hardness development in a coating composition. The coating compositions can be used to prepare clear coat or pigmented coatings for automotive OEM, auto refinish, and other applications.

We claim: 
     
       1. A thermosetting coating composition, comprising:
 (A). about 2 to about 50 weight percent, based on the total weight of (A), (B), and (C) of a curable polyester, consisting of
 i. diacid residues, comprising about 20 to 100 mole percent, based on the total moles of diacid residues, of the residues of isophthalic acid; 
 ii. diol residues, comprising about 10 to 100 mole percent, based on the total moles of diol residues, of the residues of 2,2,4,4-tetramethyl-1,3-cyclobutanediol; and 
 iii. about 2 to about 40 mole percent of the residues of at least one polyol, based on the total moles of diol and polyol residues; 
 wherein said curable polyester has a number average molecular weight of about 500 to about 10,000 daltons, a glass transition temperature of about −35° C. to about 100° C., a hydroxyl number of about 20 to about 300 mg KOH/g of polyester, and an acid number of 0 to about 80 mg KOH/g of polyester; 
 
 (B). about 25 to about 88 weight percent, based on the total weight of (A), (B), and (C) of at least one acrylic copolymer of ethylenically unsaturated monomers comprising at least one hydroxyl, epoxy, carboxyl, blocked phenol, or acetoacetoxy functional group; and 
 (C). about 10 to about 50 weight percent, based on the total weight of (A), (B), and (C), of at least one crosslinker comprising at least one compound reactive with a carboxylic acid or a hydroxyl group; 
 (D). about 10 to about 60 weight percent, based on the total weight of (A), (B), (C), and (D) of at least one non-aqueous solvent. 
 
     
     
       2. The coating composition according to  claim 1  wherein said diacid residues (i) comprise about 30 to about 70 mole percent of the residues of isophthalic acid, and further comprise about 70 to about 30 mole percent of the residues of adipic acid; and said diol residues (ii) comprise about 20 to 100 mole percent of the residues of 2,2,4,4-tetramethyl-1,3-cyclobutanediol. 
     
     
       3. The coating composition according to  claim 2  wherein said diacid residues (i) comprise about 40 to about 60 mole percent of the residues of isophthalic acid and about 60 to about 40 mole percent of the residues of adipic acid. 
     
     
       4. The coating composition according to  claim 1  wherein said diacid residues (i) further comprise up to 30 mole percent of the residues of at least one dicarboxylic acid chosen from phthalic acid, terephthalic acid, tetrachlorophthalic acid, dodecanedioic acid, sebacic acid, azelaic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, hexahydrophthalic acid, tetrahydrophthalic acid, maleic acid, fumaric acid, succinic acid, 2,6-naphthalenedicarboxylic acid, and glutaric acid. 
     
     
       5. The coating composition according to  claim 1  wherein said diol residues (ii) further comprise up to 90 mole percent of the residues of at least one diol chosen from neopentyl glycol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, hexaethylene glycol, heptaethylene glycol, octaethylene glycol, nonaethylene glycol, decaethylene glycol, 1,3-propanediol, 2,4-dimethyl-2-ethyl-hexane-1,3-diol, 2,2-dimethyl-1,2-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2,4-tetramethyl-1,6-hexanediol, thiodiethanol, 1,2-cyclohexane-dimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2,4-trimethyl 1,3-pentanediol, p-xylenediol, hydroxypivalyl hydroxypivalate, 1,10-decanediol, and hydrogenated bisphenol A. 
     
     
       6. The coating composition according to  claim 1  wherein said polyol residues (iii) comprise about 3 to about 30 mole percent of the residues of at least one polyol chosen from trimethylolpropane, pentaerythritol, trimethylolethane, erythritol, threitol, dipentaerythritol, sorbitol, and glycerine. 
     
     
       7. The coating composition according to  claim 1  wherein said curable polyester consists of said diacid residues (i) comprising about 50 to about 100 mole percent of the residues of isophthalic acid and 0 to about 50 mole percent of the residues of adipic acid, said diol residues (ii) comprising about 100 mole percent of the residues of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and said polyol residues (iii) comprising about 10 mole percent of the residues of trimethylolpropane, and wherein said curable polyester has a hydroxyl number of about 30 to about 250 mg potassium hydroxide per gram of polyester, an acid number of about 2 to about 15 mg potassium hydroxide per gram of polyester, a Tg of about −20 to about 50° C., and a number average molecular weight of about 700 to about 7000 daltons. 
     
     
       8. The composition of  claim 1 , wherein said ethylenically unsaturated monomers of the acrylic copolymer (B) are chosen from at least one of acrylate, methacrylate, styrene, (meth)acrylic acid, and vinyl esters. 
     
     
       9. The coating composition according to  claim 1  wherein said crosslinker (C) comprises at least one compound chosen from epoxides, melamines, isocyanates, and isocyanurates. 
     
     
       10. The coating composition according to  claim 9  wherein said crosslinker (C) comprises at least one epoxide compound chosen from epoxy resins containing bisphenol A, epoxy novalac resins, epoxy resins containing bisphenol F, and triglycidylisocyanurate. 
     
     
       11. The coating composition according to  claim 9  wherein said crosslinker (C) comprises at least one melamine compound chosen from hexamethoxy-methylmelamine, tetramethoxymethylbenzoguanamine, tetramethoxymethylurea, and mixed butoxy/methoxy substituted melamines. 
     
     
       12. The coating composition according to  claim 9  wherein said crosslinker (C) comprises at least one compound chosen from toluene diisocyanate, isocyanurates of toluene diisocyanate, diphenylmethane 4,4′-diisocyanate, isocyanurates of 4,4′-diisocyanate, methylenebis-4,4′-isocyanatocyclohexane, isophorone diisocyanate, isocyanurates of isophorone diisocyanate, the biuret of 1,6-hexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, isocyanurates of 1,6-hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate, p-phenylene diisocyanate, and triphenylmethane 4,4′,4″-triisocyanate, tetramethyl xylene diisocyanate, metaxylene diisocyanate, polyisocyanates, 1,4-butylene diisocyanate, methylene bis(4-cyclohexyl isocyanate), isophorone diisocyanate and isocyanate-terminated adducts of ethylene glycol, 1,4-butylene glycol, and trimethylol propane. 
     
     
       13. The coating composition according to  claim 1  wherein said solvent (D) comprises benzene, xylene, mineral spirits, naptha, toluene, acetone, methyl ethyl ketone, methyl n-amyl ketone, methyl isoamyl ketone, n-butyl acetate, isobutyl acetate, t-butyl acetate, n-propyl acetate, isopropyl acetate, ethyl acetate, methyl acetate, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, isobutanol, ethylene glycol monobutyl ether, propylene glycol n-butyl ether, propylene glycol methyl ether, propylene glycol monopropyl ether, dipropylene glycol methyl ether, diethylene glycol monobutyl ether, trimethylpentanediol mono-isobutyrate, ethylene glycol mono-octyl ether, diacetone alcohol, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, or combinations thereof. 
     
     
       14. The coating composition according to  claim 1  which comprises about 25 to about 35 weight percent of said solvent (D) and about 20 to about 35 weight percent of said crosslinker (C), wherein said crosslinker (C) comprises hexamethoxymethylmelamine. 
     
     
       15. The coating composition according to  claim 1  further comprising at least one coating additive chosen from leveling agents, rheology agents, flow control agents, plasticizers, flatting agents, pigment wetting and dispersing agents, crosslinking catalysts, pigments, dyes, ultraviolet light absorbers, ultraviolet light stabilizers; defoaming agents, antifoaming agents, anti-settling agents, anti-sag agents, bodying agents, anti-skinning agents; anti-flooding agents, anti-floating agents, and corrosion inhibitors. 
     
     
       16. A shaped object coated with the coating composition of  claim 1 .